Question

The radius of the base and height of a cylinder are in the ratio of
7:9. If volume of the cylinder is 1386 cm3, find the radius of the
base.
(Ans: 7 cm)


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Answer 1

Answer:

The radius of the base is 7 cm.

Explanation:

r/h = 7/9

r = (7/9)h

Volume of the cylinder = π r² h

1386 = (22/7) {(7/9)h}² x h

1386 = (22/7) (49/81) h² x h

1386 = {(22 x 7)/81} h³

h³ = (1386 x 81) / (22 x 7)

h³ = 112266 / 154

h³ = 729

Taking cube roots on both the sides,

h = ∛729

h = 9 cm

Substituting h = 9 cm in r = (7/9)h, we get,

r = (7/9)h

r = (7/9) x 9

r = 7 cm